Internal-combustion turbine power plant



March/27,1951

R. H. H. BARR 6,420

INTERNAL-COMBUSTION TURBINE POWER PLANT Filed March 27, 1945 Inventor Mai/301w y Q42 4 MM A Home y Patented Mar. 27, 1951 UNITED STATES TENT ()F i QE INTERNAL-COMBUSTIIQN TUREHNE POWER PLANT British company Application March 27, 19 15, SerialNo. 585,166 In Great Britain March 28, 19M

6 Claims. 1

This invention relates to internal combustion turbine power plants of the type, referred to herein as-double compound engines, having two mechanically independent rotors capable of running at different speeds, each of which consists of acompressor assembled as a single rotary unit with a turbine, and ducting interconnecting said rotors so that air passes successively and in the order named through the low and high pressure compressors, combustion means in which fuel is injected and burnt continuously, and the high and low pressure turbines in which the gaseous products of combustion expanded so as to cause them to drive their respective compressors. The references herein and in the appended claims to engines of the type referred to is to be read as meaning an engine having the characteristics described in the foregoing, and as including modi 'fications thereof in which the useful power, and

' turbine.

Itis an object of the invention to adapt an en gine of the type referred to for use as an aircraft propulsion unit driving a tractor propeller, that is, a bladed propulsion means which is at the leading end of the unit, considered in relation to the'direction of flight. It isdesirable that in such 'a case the reduction ratio of an gearing between the power unit and the propeller should be kept as low as possible. Difficulty arises, however, in the case of a tractor propeller, particularly if an axial flow turbine is employed, in

achieving this desirable end whilst at the same time attaining the degree of compactnessdemanded of an aircraft power unit and satisfying the-further requirement that the low pressure turbine should exhaust in a downstream direction, without introducing undesirable complication into the ducting. All these difficulties are met in'the present invention, by adopting an arrangement of a double compound engine of the type referred to in which the high pressure turbine, which drives the high pressure coinpressor, and the low pressure turbine, which drives the low pressure compressor, are located at opposite ends of the engine with the low pressure turbine placed at the rear or downstream end (considered in relation to the direction of flight) and by employing a high pressure turbine of the kind having independent rotors, of which one drives the tractor propeller and the other the high pressure compressor.

The arrangement of the turbines, at opposite ends of the engine with the low pressure turbine at the rear end, which in itself forms thesubject of co-pending application Serial No. 558,624,1iled October i9, 19%, and now matured into Patent Number 2,504,414, offers considera ie advantages from the point of view of compactness of con struction combined with ducting efficiency, as is pointed out in the specification of the said 00- pending application, whilst the use of a high pressure turbine with independently rotatable elements offers the possibility of designing for a much lower rotational speed of the element used for the propeller drive than that at which the high pressure turbine would normally run. Thus the problem of diving a tractor propeller in the arrangement according to said Patent No. 2,504,414, for which purpose that arrangement is not suitable owing to the position of the low pressure turbine, is advantageously solved.

According to the invention, the high pressure turbine comprises a rotary casing element which is free to rotate under the action of the expanding gases, and shaft power is taken, either directly or through gearing if necessary, from this rotary casing element.

The invention will now be more particularly described with reference to the embodiment illustrated, by way of example, in the accompanying drawing which is a sectional elevation taken through the longitudinal axis of a double compound internal combustion turbine engine for aircraft propulsion.

In the drawing the skin of the nacelle enclosing the double compound engine is indicated at iii, and toward the rear of the nacelle are provided inwardly and forwardly directed inlet ducts H which are connected at their inner ends to a fixed duct ring 52. This duct ring 12 is secured to the inlet end of the stator casing 53 of a low pressure compressor of the axial flow type, said stator casing 53 having axially spaced circumferential rows of stator blades M with which rows of blades is carried by a rotor drum E5 inter- .digitate, whilst the forward end of the stator casing 53 is connected through a short stationary duct ring ii to the inlet end of the stator casing 3 E3 of a high pressure compressor of the axial flow type. The stator casing I8 has axially spaced circumferential rows of stator blades i9 which interdigitate with rows of rotor blades on a rotor drum 2i, and the outlet end of the stator casing 88 is connected by a short duct ring 22 to the inlet of a combustion chamber 23 of annular form and into which fuel is injected and burned continuously by burner jets 2 t.

The compressor rotors i6, 28 are coaxial and mechanically independent so that they can operate at different rotational speeds, and they are driven by the coaxial rotors 25, 2'5 respectively of low and high pressure turbines 'of the axial flow type. In this connection the low pressure turbine rotor 2s, which carries rows or rotor blades 2'! interdigitating with stator blades 28 on a turbine stator casing 29, has its shaft 36 connected to a conical extension on the rear end of the compressor rotor is, which extension is enclosed in a conical housing 32 connected to the duct ring I2 and carrying in its apex the rear bearing 33, whilst the turbine stator casing 29 is supported from said housing 32 b a diaphragm 34. The forward end of the compressor rotor i5 and the rear end of the compressor rotor 29 are similarly supported for rotation by diaphragms 35, 36 respectively, hollow axial shaft extensions of which are engaged in bearings 37, 38 respectively, said bearings 3?, 38 being mounted in a centre housing 39 formed integrally with the duct ring I7. is connected to the high pressure turbine rotor 26, which drives it, by means of a forwardly extending conical extension 39 secured to the shaft 0 4! of the turbine rotor 26 and mounted in a front bearing 42 carried in the forward end of a conical housing 53 which is connected to the duct ring 22.

The high pressure turbine rotor 26 has a row of rotor blades 4 which operates between rows of blades s5 carried by a rotary casing lii which is supported for free rotation within a fixed enclosing casing 8! and in an opposite direction to the said rotor 26, under the action of the expanding gases. In this latter connection the rotary casing 46 is supported by a diaphragm 58 upon a bearing es about the rotor shaft and, at the forward side of the rotor 23, is provided with a disc 5| connected to a forwardly extending power take-off shaft 52 which is coaxial with the turbine rotor shaft 4!. The fixed casing 51, which is provided with inlet and outlet guide vanes 53, 54 respectively for the high pressure turbine, is supported at its rear side by a diaphragm 55 secured to the housing :33, and it directly receives the gases discharged from the combustion chamber 23, whilst the front wall of said casing e1 carries a bearing 56 for the power take off shaft52.

The contra-rotating elements 57, 58 of a tractor airscrew at the forward end of the engine nacelle ID are driven from the power take-off shaft 52 through reduction gear 59 and concentric shafts indicated by the reference 65.

Pipe conduits 6 l, in which reheating fuel burners 62 are located, connect the high pressure turbine exhaust to the low pressure turbine inlet.

In operation, air drawn into the inlet ducts l i from the boundary layer passing over the engine nacelle it passes through the low and high pressure compressors in series to the combustion chamber 23, and the hot gases from the latter are then expanded through the high pressure turbine so as to drive the high pressure turbine compressor rotor 26, 2E! and also, through the The high pressure compressor rotor 2d 3 rotary casing 45, power take-off shaft 52, reduction gear 59, concentric shafts so, and the contrarotating elements 51, 58 of the tractor propeller or airscrew. The exhaust gases from the high pressure turbine pass through the pipe ducts 6!, in which they are re-energised by the reheating burner jets 62, and are then further expanded through the low pressure turbine so as to drive the low pressure turbine-compressor rotor 25, It.

Any residual energy of the exhaust gases from the low pressure turbine may be utilised in the form of a propulsion jet or jets in known manner.

What I claim as my invention and desire to secure by Letters Patent is:

1. An internal combustion turbine aircraft power plant of the compound type operating on the constant pressure cycle, comprising combustion chamber means in which fuel is burnt continuously, low and high pressure compressors arranged coaxially to the rear of the combustion chamber means (considered in relation to the direction of flight) and through which air passes in series to said combustion chamber means, mechanically independent high and low pressure turbines through which the products of combustion from said combustion chamber means are expanded in series so as to drive said turbine rotors, said high pressure turbine having independently rotatable rotor elements, one element of the high pressure turbine and the low pressure turbine being operatively connected to the high and low pressure compressor rotors respectively so as to drive them, and the other independently rotatable element of the high pressure turbine having a forwardly extending propeller driving shaft driva'bly connected thereto.

2. An internal combustion turbine aircraft power plant of the compound type operating on the constant pressure cycle, comprising coinbustion chamber means in which fuel is burnt continuously; low and high pressure compressors of the axial flow type arranged co-axially and in series to the rear of the combustion chamber means (considered in relation to the direction of flight), the air passing through the flow annuli of said compressors being discharged from the high pressure compressor into said combustion chamber means; a high pressure turbine of the axial flow type, arranged forwardly of said combustion chamber means (considered in relation to the direction of flight) and co -axially with the high pressure compressor, having independently rotatable rotor elements and through the flow annuli of which the products of combustion from the combustion chamber means are expanded so as to drive said elements, on of said elements being operatively connected to the rotor of the high pressure compressor so as to drive it; a low pressure turbine of the axial flow type arranged (in relation to the direction of flight) to the rear of and co -axially with the low pressure compressor, said low pressure turbine having a rotor operatively connected to the rotor of the low pressure compressor so as to drive it; ducting connecting the forward facing exhaust of the high pressure turbine to the inlet of the low pressure turbine; and a power take-off shaft driven by and extending forwardly from the second rotor element of the high pressure turbine.

3. As an aircraft power plant for driving a tractor propeller, a double compound internal combustion turbine engine of the kind referred to, comprising in combination a low pressure rotor consisting of a low pressure compressor and a low pressure turbine, and a high pressure rotor consisting of a high pressure compressor and a high pressure turbine, rotatable independently of each other and arranged coaxially so that the low pressure turbine, low pressure compressor, high pressure compressor, and high pressure turbine are in that serial order from rear to front of the power plant (considered in relation to the direction of fiight), said high pressure turbine having independently rotatable elements, of Which one constitutes the turbine element of the high pressure rotor; and a propeller driving shaft drivingly connected to the other of said high pressure turbine elements and extending forwardly to provide a power take-oif in front of the power plant.

4. As an aircraft power plant for driving a tractor propeller a double compound internal combustion turbine engine or the kind referred to, comprising in combination a low pressure rotor consisting of a low pressure compressor and a low pressure turbine, and a high pressure rotor consisting of a high pressure compressor and a high pressure turbine, rotatable independently of and arranged coaxially adjacent to one another so that the low pressure turbine, 10W pressure compressor, high pressure compressor, and high pressure turbine are in that serial order from rear to front of the propulsion unit (considered in relation to the direction of flight), said high pressure turbine having independently rotatable rotor elements, of which one constitutes the tur bine element .of the high pressure rotor, and the ir entry being at the rear end of the low pressure compressor; combustion means between the high pressure compressor and high pressure turbine; ducting interconnecting all the components to provide a flow path through the low and high pressure compressors, combustion means, and high and low pressure turbines in that order, with reversal of the general direction of flow between the turbines; and a power take-off shaft drivingly connected to the other of said high pressure turbine elements and extending forwardly to provide a power take-oil in front of the pow 1' plant.

5. An aircraft power plant as claimed in claim 4, further characterised by the feature that the turbines are of the axial flow type.

6. As an aircraft power plant for driving a tractor propeller, a double compound internal combustion turbine engine of the kind referred to, comprising in combination a low pressure rotor consisting of a low pressure compressor and a low pressure turbine and a high pressure rotor consisting of a high pressure compressor and a high pressure turbine rotatable independently of and arranged co-axially adjacent to one another so that the low pressure turbine, low pressure compressor, high pressure compressor, and high pressure turbine are in that serial order from rear to front of the propulsion unit (considered in relation to the direction of flight), said high pressure turcine having independently rotatable rotor elements, of which one constitutes the turbine element of the high pressure rotor, and the air entry being at the rear end of the low pressure compressor; combustion means annularly disposed between the high pressure compressor and high pressure turbine; ducting inter-connec ing said compressors, turbines combustion means which is disposed symmetrically about their common axis and is so constructedand arranged as to provide a general direction of flow in the intended direction of flight through the low and high pressure compressors, combustion means, and high pressure turbines in that order, and flow contrary to the intended direction of night from the high pressure to the low pressure turbine, said inter turbine ducting being symmetrically disposed about said common axis, air inlet conduits to the low pressure compressor in let likewise symmetrically disposed and crossing over said inter-turbine ducting in the region of said inlet, whereby there is intersection of flow paths of air entering the compressor and gas entering the turbine; and a propeller driving shaft drivingly connected to the other of said high pressure turbine elements and extending forwardly to provide a power tal ze-off in front of the power plant.

RICHARD HENRY HOVJARD BARR.

REFERENCES CITED The following references are of record in the lie of this patent:

UNITED STATES PATENTS Number Name Date 911,825 Lentz Feb. 9, 1909 996,324 De Ferranti June 27, 1911 2,050,349 Lysholrn et al. Aug. 11, 1936 2,095,991 Lysholrn Get, 19, 1937 2,318,905 Traupel May 11, 1943 2,326,372 Seippel Aug. 3, 1943 2,329,046 Larrecq Apr. 23, 1946 2,454,738 Hawthorne Nov. 23, 1948 2,476,179 Cameron July 12, 1949 FOREIGN PATENTS Number Country Date 334,519 Germany Sept. 19, 1917 OTHER REFERENCES Flight, Feb. 17, 1944, page 171. 

